Merge tag 'trace-v6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Remove useless assignment of soft_mode variable

   The function __ftrace_event_enable_disable() sets "soft_mode" in one
   of the branch paths but doesn't use it after that. Remove the setting
   of that variable.

 - Add a cond_resched() in ring_buffer_resize()

   The resize function that allocates all the pages for the ring buffer
   was causing a soft lockup on PREEMPT_NONE configs when allocating
   large buffers on machines with many CPUs. Hopefully this is the last
   cond_resched() needed to be added as PREEMPT_LAZY becomes the norm in
   the future.

 - Make ftrace_graph_ent depth field signed

   The "depth" field of struct ftrace_graph_ent was converted from "int"
   to "unsigned long" for alignment reasons to work with being embedded
   in other structures. The conversion from a signed to unsigned caused
   integrity checks to always pass as they were comparing "depth" to
   less than zero. Make the field signed long.

 - Add recursion protection to stack trace events

   A infinite recursion was triggered by a stack trace event calling RCU
   which internally called rcu_read_unlock_special(), which triggered an
   event that was also doing stacktraces which cause it to trigger the
   same RCU lock that called rcu_read_unlock_special() again.

   Update the trace_test_and_set_recursion() to add a set of context
   checks for events to use, and have the stack trace event use that for
   recursion protection.

 - Make the variable ftrace_dump_on_oops static

   The cleanup of sysctl that moved all the updates to the files that
   use them moved the reference of ftrace_dump_on_oops to where it is
   used. It is no longer used outside of the trace.c file. Make it
   static.

* tag 'trace-v6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  trace: ftrace_dump_on_oops[] is not exported, make it static
  tracing: Add recursion protection in kernel stack trace recording
  ftrace: Make ftrace_graph_ent depth field signed
  ring-buffer: Avoid softlockup in ring_buffer_resize() during memory free
  tracing: Drop unneeded assignment to soft_mode

1 files changed, 7 insertions, 1 deletions

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6f2148df14d9..baec63134ab6 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -138,7 +138,7 @@ cpumask_var_t __read_mostly	tracing_buffer_mask;
  * by commas.
  */
 /* Set to string format zero to disable by default */
-char ftrace_dump_on_oops[MAX_TRACER_SIZE] = "0";
+static char ftrace_dump_on_oops[MAX_TRACER_SIZE] = "0";
 
 /* When set, tracing will stop when a WARN*() is hit */
 static int __disable_trace_on_warning;
@@ -3012,6 +3012,11 @@ static void __ftrace_trace_stack(struct trace_array *tr,
 	struct ftrace_stack *fstack;
 	struct stack_entry *entry;
 	int stackidx;
+	int bit;
+
+	bit = trace_test_and_set_recursion(_THIS_IP_, _RET_IP_, TRACE_EVENT_START);
+	if (bit < 0)
+		return;
 
 	/*
 	 * Add one, for this function and the call to save_stack_trace()
@@ -3080,6 +3085,7 @@ static void __ftrace_trace_stack(struct trace_array *tr,
 	/* Again, don't let gcc optimize things here */
 	barrier();
 	__this_cpu_dec(ftrace_stack_reserve);
+	trace_clear_recursion(bit);
 }
 
 static inline void ftrace_trace_stack(struct trace_array *tr,